Interpretive Summary: Subgroup J avian leukosis virus (ALV-J) is an emerging and economically important virus infection that can cause cancer-like disease in meat-type chickens. Control of this important disease is complicated by lack of reliable specific methods for detection of causative virus. We have modified molecularly an embryonic avian cell line termed DF-1 cell line by inserting part of the genetic code of ALV-J into the genome of DF-1 cells. This modification rendered the cell line resistant to infection with ALV-J, but still susceptible to infection with all other subgroups of ALV. This newly developed cell line is an important diagnostic tool to differentiate between infection with ALV-J and other subgroups of ALV and should be useful to poultry disease diagnosticians in industry and academia.

Technical Abstract:
A cell line (DF-1\J) expressing the envelope isolated from the ADOL-Hc1 strain of the avian leukosis virus subgroup J (ALV-J) was used to analyze receptor interference to six different isolates of ALV-J as well as ALV subgroups A-E. The traditional gag-specific ELISA assay as well as flow cytometry was used to evaluate viral infection. The parental cell line (DF-1) was susceptible to all ALV subgroups tested while the DF-1\J cell line was selectively resistant to the subgroup J isolates. The DF-1\J cell line was completely resistant to infection by five of the six ALV-J isolates as determined using the Gag-specific ELISA assay. The interference to the sixth ALV-J isolate, ADOL-5701, was significant but incomplete. There was no interference to the other ALV subgroups (A-E) induced by the expression of the ADOL-Hc1 envelope. The ALV-J isolates used in this analysis are serologically distinct when analyzed by flow cytometry. Convalescent sera to ADOL-Hc1 cross reacts to all of the ALV-J isolates tested however sera to HPRS-103 did not bind to four of the six isolates. Based on the intensity and differential binding of these antisera using flow cytometry, the six ALV-J isolates used can be grouped into four categories. The serologic differences are confirmed by the envelope nucleotide sequence polymorphisms observed between ADOL-Hc1 and HPRS-103. Thus the DF-1\J cell line is resistant to infection by a serologically and genetically diverse group of ALV-J isolates and should be useful as a diagnostic tool.